Octane 87, 91 and 93

[shane_th_ee]

What about MPG differences? Anybody hand-calc their mileage and has measured a difference between running on different octane ratings?

I didn't do a long and detailed study, but initial estimates showed about a 10% gain in fuel efficiency while towing, so I've been running 91 Octane all summer. Why take a performance hit if the savings from using 87 Octane is offset because you use more of it?

 

[NASCAR Mike]

I think Ford has been rating their HP using the higher octane for quite some time. My 2013 Mustang GT was rated at 420HP with a small note that is was 400HP using 87 octane.

My 2005 Ford Excursion with 6.0 turbo diesel was rated as 325 HP and 560 torque on 50 cetane diesel. I could never find anything higher than 40 cetane at most places and I think it was 42 cetane using B5 bio-diesel.

 

[rumline]

I didn't do a long and detailed study, but initial estimates showed about a 10% gain in fuel efficiency while towing, so I've been running 91 Octane all summer. Why take a performance hit if the savings from using 87 Octane is offset because you use more of it?

10% gain might make it worthwhile. Most places around here have 91 octane for 10% more than 87 (~$3.35 vs ~$3.05). Here in Colorado they try to pass off 85 octane as "regular" so we don't get an 89 option. For towing I'd definitely run 91 but for around town...I guess I'll just have to run my own test. JohnT reported ~5% gain in efficiency using 91, so if my results are closer to his then I'll probably stick with the swill.

 

[3rd Expyowner123]

These are great comments that interest me. In Feb. I test drove my Ford Dealer's personal Platinum Expedition. I noticed that the throttle response didn't seem as smooth as the XLT or Limited Models I test drove. I ended up ordering a Limited, 4 X 4, HD Trailer Tow. My truck exhibits similar throttle response as the Platinum. I suspect my Limited has the higher HP tuned engine. I typically run regular gas, however I have filled up with Premium (93 octane) a few times. I think the throttle response is noticeable smoother when I run premium. I have not run hard my truck, so I cannot comment on acceleration. As other comments note is this feed, the owners manual states running regular octane is fine but it recommends premium. I live in a hot climate, and the manual states the performance on premium fuel will be more noticeable in hot weather.
As far literature on the Expedition, it states that the Platinum when running premium fuel has additional horsepower.

 

[NyackRob79]

Turbocharged engines work a little differently than the traditional naturally aspirated. Because the turbo packs more air into each cylinder, the chance of knocking is much higher. I generally use 91 or higher on any turbocharged engine, period.

 

[JCP2018]

I've run 87 since purchase, and average around 21 on road trips, 17 in the city pretty consistently. I would run a couple of tanks of 93 (or boat fuel 100% gas) but, due to being an EL and having that huge fuel tank, I'm already clutching my chest at the thoughts of $80 fill-ups; 87 around here can be found for about $2.50 with discounts, but premium is over $3 (more than diesel in some stations), and would push my bill over $100, aside from being about 20% more expensive (if 10% is the average improvement it would make no economic sense to run it). Being on a fixed income that hurts. However, once bills are paid, and we're down to one car payment, I may start running the higher octane just to see if there is any improvement.

I try to improve efficiency in other areas; fuel efficient tires properly inflated, regular alignments, slow down, etc. I also run oil formulated for DI engines and am trying a few additives that claim to clean up the carbon. Put Lucas in the tank every other fill. One of these days I'm going to head out west and try to create the perfect storm to see how much range I can truly get, with my goal being 1,000 miles on a single tank (max inflated tires, fresh oil change, highest octane boat fuel with new filter, fresh air filter, all the junk out of the car except needed supplies and tuned; otherwise all factory stuff stays on).

 

[JExpedition07]

I've run 87 since purchase, and average around 21 on road trips, 17 in the city pretty consistently. I would run a couple of tanks of 93 (or boat fuel 100% gas) but, due to being an EL and having that huge fuel tank, I'm already clutching my chest at the thoughts of $80 fill-ups; 87 around here can be found for about $2.50 with discounts, but premium is over $3 (more than diesel in some stations), and would push my bill over $100, aside from being about 20% more expensive (if 10% is the average improvement it would make no economic sense to run it). Being on a fixed income that hurts. However, once bills are paid, and we're down to one car payment, I may start running the higher octane just to see if there is any improvement.

I try to improve efficiency in other areas; fuel efficient tires properly inflated, regular alignments, slow down, etc. I also run oil formulated for DI engines and am trying a few additives that claim to clean up the carbon. Put Lucas in the tank every other fill. One of these days I'm going to head out west and try to create the perfect storm to see how much range I can truly get, with my goal being 1,000 miles on a single tank (max inflated tires, fresh oil change, highest octane boat fuel with new filter, fresh air filter, all the junk out of the car except needed supplies and tuned; otherwise all factory stuff stays on).

Your gas is cheap. Costs me $80 to fill up my standard length with 87. NY and their stupid taxes. I’m fine paying for the gas it’s worth it, sounds like you need to buy a boat. Once you fill that up you’ll think the expy is a econobox.